Thirty four eyes which underwent vitrectomy because of diabetic proliferative retinopathy were reviewed. The overall success rate of the operation was 62%. Excluding table top retinal detachments, which all did badly, the success rate was 72%. Grading by ultrasound was found to be helpful in; (a) planning surgical approach, (b) assessing visual outcome. The most common late complication was cataract. Extracapsular cataract extraction with implantation was found to be successful in these cases.